I cannot see how weighing the van will help the op with the weight limits for his van.
The plate tells him the maximum weights he can legally carry.
The weighbridge tells him the actual weight of the van.
How are these two things connected?
Oldun, the two are connected -
The maximum weights he can legally carry are shown on his registration document (and for the moment we must assume that this is correct and matches the illegible plate).
The weighbridge tells him the actual weight of the van, thus it is either above or below (or the same as, unlikely) the weight on his V5.
By weighing the van fully laden he can determine whether he is 'legal' or not iro Gross Vehicle weight.
Riverboat has researched the possible configurations for his van and concluded that the front axle should not exceed 1500kg, the rear 1700kg and the gross 3100kg. This corresponds with the V5 assertion of 3100kg revenue weight.
Adding the two gross axle weights permitted gives 3200kg, thus there is a loading tolerance of 100kg between the axles.
If Riverboat weighs each axle at the weighbridge (in accordance with Sprokits excellent article), he can determine whether he is above or below the maximum permitted axle weight that he has concluded from his research.
Thus the 'two' are connected and will allow him to determine whether his use of the vehicle is compliant or not in terms of weights), assuming that his conclusions are correct.
There is a legal requirement for a legible plate to be affixed to the vehicle, and he should attempt to obtain a replacement plate and have it affixed in the appropriate place.